1. Field of the Invention
The present invention relates to an image sensor package and its manufacturing method.
2. Description of the Related Art
In general, an image sensor is a device for sensing subject information and converting the sensed subject information into an image signal. Such an image sensor is roughly divided into two types, that is, a camera tube and a solid image sensor; the former includes a vidicon, a plumbicon, etc., and the latter includes a Complementary Metal Oxide Semiconductor (CMOS), a Charge Coupled Device (CCD) or the like. Among other things, the solid image sensor is currently manufactured in such a manner that a barrel having a lens is coupled to a CMOS image sensor die or a CCD image sensor die.
As an example, a conventional image sensor package includes a substrate, an image sensor die adhered on the substrate, electrically conductive wires for electrically connecting the substrate and the image sensor die to each other, a mount holder attached on the substrate along outer peripheries of the image sensor die and the wires, and a barrel having a lens and coupled to the mount holder.
Of course, an external image passes through the lens of the barrel and is then converted into an electrical signal in the image sensor die, and the converted electrical signal is delivered to an external device via the wires and the substrate.
In such a conventional image sensor package, however, there is a problem in that the image sensor die is wholly exposed to the outer atmosphere during sawing, die attaching and wire bonding processes, so that its optical performance becomes deteriorated. That is, during the sawing process in which a wafer is sawn into image sensor die pieces by a diamond blade, etc., many particles are generated and thus the image sensor die is contaminated with the particles, which results in lowering in optical performance of the image sensor die. The image sensor die is also contaminated with particles during the die attaching and wire bonding processes, in which it is attached to the substrate and wires are bonded between the image sensor die and the substrate, thereby becoming further deteriorated in its optical performance.
Moreover, the conventional image sensor package has another problem in that the whole package has a large width because the mount holder and the barrel are adhered on the substrate along the outer periphery of the image sensor die. In other words, the mount holder and the barrel, which are only secondary components, have larger widths than that of the image sensor die which practically processes the external image, thereby unnecessarily enlarging the width of the package.
Furthermore, the conventional image sensor package is less reliable because the wires are not encapsulated by an encapsulant, but exposed to air, so that they may be contaminated and easily oxidized.